Q.1 Which of the following is a measure of a material's stiffness?
Density
Young's modulus
Poisson's ratio
Bulk modulus
Explanation - Young's modulus is a measure of the stiffness of a material, defined as the ratio of stress to strain in the elastic region.
Correct answer is: Young's modulus
Q.2 Poisson's ratio is defined as:
Longitudinal strain / Lateral strain
Lateral strain / Longitudinal strain
Stress / Strain
Bulk modulus / Shear modulus
Explanation - Poisson's ratio is the ratio of lateral strain to longitudinal strain when a material is stretched.
Correct answer is: Lateral strain / Longitudinal strain
Q.3 Which of the following remains constant for a perfectly elastic material?
Stress beyond yield point
Ratio of stress to strain in elastic limit
Plastic deformation
Strain energy density
Explanation - For a perfectly elastic material, the ratio of stress to strain remains constant within the elastic limit.
Correct answer is: Ratio of stress to strain in elastic limit
Q.4 The elastic potential energy stored per unit volume of a stretched wire is given by:
1/2 × Stress × Strain
Stress / Strain
Young’s modulus × Strain
1/2 × Stress² / Young’s modulus
Explanation - The energy per unit volume (strain energy density) in a stretched wire is (1/2) × (Stress² / Young’s modulus).
Correct answer is: 1/2 × Stress² / Young’s modulus
Q.5 Shear modulus relates which of the following quantities?
Shear stress and lateral strain
Normal stress and longitudinal strain
Volumetric stress and volumetric strain
Stress and energy density
Explanation - Shear modulus (G) is the ratio of shear stress to shear strain.
Correct answer is: Shear stress and lateral strain
Q.6 The relation between Young’s modulus (Y), Shear modulus (G), and Poisson’s ratio (σ) is:
Y = 2G(1 + σ)
Y = G / (1 - 2σ)
Y = 3G(1 - 2σ)
Y = 2G(1 - σ)
Explanation - The relation is Y = 2G(1 + σ), linking elastic constants in isotropic materials.
Correct answer is: Y = 2G(1 + σ)
Q.7 Which of the following materials typically has the highest Young’s modulus?
Rubber
Steel
Wood
Lead
Explanation - Steel is very stiff and has a high Young's modulus compared to other common materials.
Correct answer is: Steel
Q.8 Hooke’s law is valid for which region of stress-strain curve?
Plastic region
Elastic region
Fracture point
Ultimate stress region
Explanation - Hooke's law applies in the elastic region, where stress is directly proportional to strain.
Correct answer is: Elastic region
Q.9 A material has a Poisson’s ratio of 0.5. What does this indicate?
Material is perfectly elastic
Material is incompressible
Material is brittle
Material has low stiffness
Explanation - Poisson’s ratio of 0.5 indicates the material is incompressible (volume does not change under stress).
Correct answer is: Material is incompressible
Q.10 The bulk modulus (K) is related to which type of stress?
Shear stress
Volumetric stress
Axial stress
Torsional stress
Explanation - Bulk modulus measures a material's response to uniform pressure (volumetric stress).
Correct answer is: Volumetric stress
Q.11 The maximum elastic strain energy in a wire occurs at:
Elastic limit
Plastic deformation
Yield point
Fracture point
Explanation - The maximum elastic energy is stored just before the material reaches its elastic limit.
Correct answer is: Elastic limit
Q.12 For a wire of length L and cross-sectional area A, the elongation due to tensile force F is inversely proportional to:
Length L
Force F
Cross-sectional area A
Young’s modulus Y
Explanation - Elongation ΔL = FL / (A Y), so it is inversely proportional to area A.
Correct answer is: Cross-sectional area A
Q.13 A rubber band obeys Hooke's law up to a certain limit. Beyond this limit, it:
Breaks immediately
Continues to stretch elastically
Exhibits plastic behavior
Becomes incompressible
Explanation - Beyond elastic limit, the rubber band shows plastic deformation before breaking.
Correct answer is: Exhibits plastic behavior
Q.14 If a cylindrical rod is stretched, the volume remains constant if Poisson’s ratio is:
0
0.25
0.5
1
Explanation - Poisson’s ratio of 0.5 indicates no change in volume under longitudinal stress.
Correct answer is: 0.5
Q.15 The ratio of bulk modulus to shear modulus for an incompressible material is:
1
2
3
∞
Explanation - An incompressible material has infinite bulk modulus, so the ratio K/G → ∞.
Correct answer is: ∞
Q.16 Which of the following is not an elastic constant?
Young’s modulus
Bulk modulus
Poisson’s ratio
Density
Explanation - Density is a physical property but not an elastic constant.
Correct answer is: Density
Q.17 The unit of shear modulus in SI system is:
Pascal
Newton
Newton/m²
Both A and C
Explanation - Shear modulus has the same unit as stress: Pascal (Pa) = N/m².
Correct answer is: Both A and C
Q.18 A steel wire is twice as long and half the area of another. If same tension is applied, elongation will be:
Same
Twice
Four times
Half
Explanation - ΔL = FL / (A Y), doubling L and halving A makes elongation 4 times.
Correct answer is: Four times
Q.19 Which type of stress leads to change in shape without change in volume?
Tensile stress
Compressive stress
Shear stress
Hydrostatic stress
Explanation - Shear stress deforms shape but does not change volume.
Correct answer is: Shear stress
Q.20 Which material is more likely to be brittle?
Glass
Steel
Rubber
Aluminium
Explanation - Brittle materials like glass break without significant plastic deformation.
Correct answer is: Glass
Q.21 In a stress-strain curve, the area under the curve up to the elastic limit represents:
Work done by external force
Elastic energy stored per unit volume
Ultimate tensile strength
Plastic energy
Explanation - Area under stress-strain curve up to elastic limit equals strain energy per unit volume.
Correct answer is: Elastic energy stored per unit volume
Q.22 Which of the following is not true for elastic deformation?
Material returns to original shape after stress is removed
Stress is proportional to strain
Permanent change in shape occurs
Obeys Hooke's law
Explanation - Elastic deformation is fully reversible; permanent change occurs in plastic deformation.
Correct answer is: Permanent change in shape occurs
Q.23 For a rod under tension, if the stress doubles, the strain:
Halves
Doubles
Remains same
Becomes zero
Explanation - Within elastic limit, stress is proportional to strain according to Hooke's law.
Correct answer is: Doubles
Q.24 Which property of a material determines its resistance to volume change?
Young’s modulus
Shear modulus
Bulk modulus
Poisson’s ratio
Explanation - Bulk modulus measures a material's resistance to uniform compression.
Correct answer is: Bulk modulus
Q.25 A material returns to its original shape after removing applied force. This property is called:
Plasticity
Elasticity
Viscosity
Ductility
Explanation - Elasticity is the property of a material to regain its shape after deformation.
Correct answer is: Elasticity